Fuel supply system



Patented Dec. 14, 1948 FUEL SUPPLY SYSTEM Frederik Barfod, South Bend,Ind., assignor to BendixAviation Corporation, South Bend, Ind., acorporation of Delaware Application May 7, 1945, Serial No. 592,397

40 Claims. (Cl. 12S-119) 'I'his invention relates to fuel supply systemsor devices for internal combustion engines and more particularly todevices or sysi Ans in which liquid fuel is supplied under positivepressure.

An important object of the invention is to provide a fuel feeding systemin which the fuel flow is automatically regulated in accordance withcertain engine variables such as, for example engine speed and engine.charging pressure.

This fuel supply system, whileespeclally applicable to fuel supplyVsystems of thecharacter hereinafter particularlydescribed, ls notlimited to such uses. but is obvious-.11,"l available, with or withoutmodification, in aI great-variety oi' cases where fuel is intended to besupplied under more or less analogous conditions in an internalcombustion engine or otheri'uel consuming device.

Further objects and advantages of the invention will be apparent, tothose skilled in the art, from the following detaileddescription, takenin connection with the accompanying drawing. Although but oneembodimentis shown, skilled persons will understand that many variations may bemade without departing from the principles disclosed, and I contemplatethe employment of any structures, arrangements, or modes said` chamber34 is being at all times substantially the same as that in passage 33,and this pressure in said chamber and passage being hereinafter referredto as pressure A or control pres'- sure. One wall of chamber 34 isclosed by a ilexible diaphragm 36 which is marginally clamped betweenthe casing 36 and a. shoulder of the body 40 of the device. Arestriction or jet 42 is provided between the passages 32 and 33 throughwhich fuel is adapted to ow.

Passage 32 is provided with a branch passage 44 which communicates withthe impeller chamber 46 of a pump, indicated generally at 41. 'I'hispump, as shown, is of the centrifugal type which includes an impellerI46 driven by they engine through a shaft di) which is suitablyconnected,

by any well known means, with said engine which system.

of operation that are properly within the vscope f of the appendedclaims. l

In the figure, which is a diagrammatic view of a fuel system embodyingthe present invention, there is shown an induction passage l@ having anair inlet l2, and a mixture outlet lt connected to the intake manifoldl@ of an internal combustion engine, not shown, or to a superchargerinlet, should a supercharger be used, the induction passage i@ beingcontrolled by a throttle valve I8. A supercharger might alternately beconnected to the inlet l2 or such a device might be connected to` both,`the inlet' I2 and the outlet lli. Liquid fuel is Supplied by a pump,indicated generally at 20, which may be Operated by the engine, or byany other suitable means, and is capable of supplyingfuel underpositive, preferably but not necessarily substantially constant,predetermined pressure. This pump may be of any wel] known type but, asshown, is of the sliding vane type having an inlet 22 receiving fuelfrom a source, anoutlet conduit 24 and The outlet of pump 4l isconnected to a passage 52 which communicates with a chamber 54 on theside of the diaphragm 38 opposite the chamber t4 by way of a meteringrestriction or iet 56 therein, the pressure of fuel in said chamber 58being at all times substantially the same as that in the passage 52posterior to the jet 56 and this pressure in chamber 5d and passage 52posterior to jet 56 will be hereinafter referred to as pressure B ormetered fuel pressure.

Chamber 5d has an outlet connected by a conduit 53 with a fuel nozzlemember 6d discharging into the induction passage posterior to thethrottle valve. Air is bled into the nozzle member 66 through crosspassages 6I in a tip portion 62 of an air tube 63 having an air passage63a therein receiving air from a tube 64 by way of a passage 65; thetube 64 being located in the air entrance I2 of the induction passageand adapted to receive the impact of air entering said induction passageTip portion 62 extends part way into the fuel passage of the nozzle andthe fuel emulsion is discharged from an annular groove 66 between theshoulder at the base of said portion 62 and the adjacent end of nozzlemember 60. The outlet for the chamber 54 is provided with a fitting 61having a bore within which a iiat sided or uted valve 68 is slidablyguided, said valve having a conical tip 69 cooperating with a` valveseat 'l0 in said fitting for controlling the discharge of fuel fromchamber 64. The

end of the valve v68 opposite the conical tip is attached tothediaphragm 38. As shown, said attached end is riveted over at 1| andwasher-like ing cut or otherwise injured thereby and providing means forretaining the adjacent ends of springs 16 'and 18 disposed respectivelyin chambers 54. and 34. These springs are preferably light and ofsubstantially the same calibration although they may have othercharacteristics. Spring 16 reacts between the"spring retainer 1 4 andone wall of the chamber 54 for urging the valve 68 in the openingdirection, while spring 18 reacts between retainer 12 and a springretainer 8|) disposed in chamber 84, said spring being adapted to urgethe valve 68 in the closing direction. The Veffective force of thesprings is adjustable, a screw 82, threadably received in an opening inthe casing 36, being provided therefor. It is to be understood thatpreferably the adjustment is such that the valve 68 is normally slightlyopen when the engine is inoperative, for a purpose to be describedhereinafter.

-The passages 52 and 33 are connected together by a conduit 86. One endof said conduit communicates with the passage 52 anterior to therestriction 66 and the other end communicates with the'passage 33, therebeing a restriction or orice 88 provided in the conduit 86. It is to belnoted that the fuel pressure in that portion of conduit 86 which is onthe centrifugal pump side of orice 88, that is between orifice 88 andconduit 62, is at all times substantially the same as the pressure inthat portion of the passage 52 anterior to jet 56 and the pressure insaid portions of the c'onduit and passage will be hereinafter referredto as pressure C.

Means for varying the effective size of orifice 88 comprises a valve 92controlled by a suction responsive device indicated generally at 93. Thevalve 92 is connected to or' formed integral with a valve stern 94slidable in a guide .96, said stern 94 being connected at-its outer endto a plate'98 forming one wall of a sealed expansible bellows enclosedby a casing |02 which is supported on the body 40 by any suitable wellknown means. The casing is subjected to engine charging pressure bymeans of a conduit |06 which communicates with said casing adjacent thelower portion thereof so as to draw oi any fuel which may seep past thestem 94, and communicates with the induction passage posterior to thethrottle valve I8, as shown. However if a supercharger is used conduit|06 is connected to the engine manifold, posterior to the supercharger.The valve 92 is therefore controlled in accordanse with engine chargingpressure which reflects throttle position and engine speed and load. Alight compression springv |08 may be provided within the bellows, anarrangement that ls particularly desirable, if the bellows is partiallyor completely evacuated, to extend the bellows to a normal balancingposition and it may be desirable for said spring and bellows to be socalibrated and arranged that the valve 92 will be normally closed whenthe pressure in the casing |02 is at its highest operating value.

It is also to be noted that the pressure in branch passage 44 is at alltimes substantially the same as that in passage 32 and the pressure insaid passages will be hereinafter referred to as pressure D or pumpinlet pressure.

Operation During normal operation fuel is supplied under pressure to theinlet 44 of the centrifugal pump 41 by means such as the fuel pump 20although 'other means may also be employed to supply fuel to said inlet44. Fuel received by pump 41 is discharged under an increased pressureinto passage 52 from which it flows through metering orifice 56 tochamber 54, past valve 61 which is opened by the pressure of fuel inchamber 54 acting on diaphragm 38, into conduitv 58, and thence to anozzle 60 or other fuel discharge means Due to the inherentcharacteristics of the centrifugal pump 41, the pressure C at the outletof pump 41 will be greater than the pump inlet pressure D by an amountwhich is directly proportional to the square of the speed of the pumpand consequently directly proportional to the square of the enginespeed.

During operation, with Vthe valve 92 in a partially open position, fuelat pressure C will flow through the calibrated restriction 88 intopassage 33 and then through orifice 42 to the pump inlet 44. As aconsequence the pressure in passage 33, herein referred to as controlpressure A, will be of a value intermediate the fuel pressure C and pumpinlet pressure D, and its value relative to the pressures C and D willdepend upon the effective size of orifice 88 relative to the area oforifice 42. For any fixed setting of valve 92, pressure A will remaingreater than pressure D and less than pressure C by amounts representingconstant percentages of the difference between pressures A and D. Thus,if orifice 88 has an effective area equal to orifice 42, pressure A willremain substantially half way between pressures C and D irrespective ofvariations in speed of pump 41. It therefore follows that thedifferential between pressures C and A will likewise vary as the squareof engine speed, for a fixed setting of valve 92.

Since the springs 16 and 18 are substantially in balance, exc'ept forconsiderations hereinafter explained, the pressure of the fuel inchamber 54, referred to herein as metered fuel pressure B, will bemaintained equal to control pressure A. In the event pressure B shouldtend to exceed pressure A the valve 61 will tend to open to allow theescape of additional fuel to the nozzle and consequent lowering ofpressurev B, and the reverse action will occur if B tends to be lessthan A. It is thus clear that the difference between pressure C andpressure B likewise will vary as the square of the enginespeed for agiven setting of Valve 92.

As is generally known, the quantity of fuel which will flow through agiven size metering orifice such as metering jet 56 will vary inproportion to the square root of the differential in pressures C and Bon opposite sides of the orifice, and since this differential varies asthe square of the engine speed, it will be apparent that the quantity offuel flowing through orilc'e 56 for a given setting of valve 92 willvary directly as the engine speed.

In view of the fact that the weight of air ow to an engine at a givenmanifold pressure varies substantially in direct lproportion to theengine speed,. except for variations caused by Variables such as exhaustback pressure and in- I take air and exhaust lpending application ofWirth and Barfod, Serial vneedle contour is such as to increase theorifice Vfuel mixture as is desired. One means for effectl gastemperatures which may be compensated for'as described in the co-l No.607,290, filed June 7, 1945, the device here described will supply fuelto the -engine in acl cordanc'e with the air flow thereto.

If at a. given engine speed the manifold or engine charging pressure isincreased, the weight of air supplied to the engine will likewiseincrease, andthe quantity of fuel suppliedto the engine should becorrespondingly increased. This increase in fuel flow is accomplishd inthe present device by the operation of valve 92. Any increase incharging pressure is transmitted, through passage |06 to chamber |02 andwill lr, cause bellows |00 to partially collapse whereupon valve 92 willreduce the effective area of the calibrated restriction 88. Y

Upon decrease in the effective area of orifice 88, pressure A will bereduced so as to more nearly approach pressure D and as a consequencethe valve 61 will open to permit discharge of fuel t0 the engine at agreater rate such that thel pressure B will be reduced to equal newpressure A. In other words, reducing pressure A reduces pressure B andthereby increases the differential between fuel pressure C and meteredfuel pressure B. Consequently, fuel is delivered through orifice 56 at agreater rate to compensatefor the increase in air flow which instigatedthe change in pressure A. By properly contouring valve 92, the effectivearea of orifice 88 may be so controlled as to obtain any desired fuel toair relationship with variations in engine charging pressure. :if

For example, at conditions of high power output, corresponding to lowintake manifold pressure it is generally desirable to increase therichness of the mixture. This may be readily accomplishecl by properlyshaping the contour of valve i' 92. If the valve 92 is arranged tomaintain the effective area of the metering orifice directlyproportional to the manifold pressure, a constant mixture ratio will beobtained. However, if the cation, Serial No. 607,290.

Provision may be made for enriching the idling ing idle enrichment is toadjust valve 6l so that 60 it is normally slightly open. Thus the fuelmetering differential pressure required to balance the diaphragm valveassembly is increased. Then at low differential pressures, correspondingto idle operation, the arrangement is of material effect in producing arelatively large increase in fuel flow, thereby providing the dcsiredrich mixture at idle. However, at high differential pressures thearrangement has a negligible effect and has substantially no effect onthe richness of the fuel mixture which is maintained at the normal fuelto air ratio.

It is thus apparent that the basic structure will provide asubstantially constant mixture richness. but by introducing anextraneous factor to effect variations in the position of valve Olas byvarying the area of the metering orifice IB, any fuel meteringcharacteristic may be obtained. Means other than pump 41 might also beused to create a pressure in passage 52 which varies as the square" ofengine speed, or other changes might be made without departing from theprinciples of the invention and I contemplate the use of any sucharrangements properly falling within the scope of the subjoined claims.

I claim: v

1. In a fuel system fer an internal combustion engine: a source of fuel;a conduit connecting said source of fuel with the engine; a pump forcreating a fuel pressure and effecting a flow of fuel through saidconduit, the quantity of which will vary directly as the engine speed;means for controlling said flow; and a passage adapted to transmit avariable controlpressure developed by said pump to said means forinfluencing the vsource of fuel; a conduit for connecting said source offuel with the engine; a pump in said conduit adapted to be driven by theengine;

means for creating a fuel pressure in and effecting a flow of fuelthrough said conduit, the quantity of which will vary directly as thespeed of said engine; means for controlling said fuel flow; and meansfor regulating the first mentioned means.

4. The invention defined by claim 3 wherein the regulator means isresponsive to an engine variable.

5. In a fuel system for an internal combustion engine: a conduit forsupplying fuel to the engine; fuel metering means in said conduit; fuelflow vcontrol means posterior to the metering means; means, having aninlet and an outlet, for supplying unmetered fuel to said metering meansat a pressure varying in response to variations in engine speed;meansfor creating a pressure in-` termediate the pressure of saidunmetered fuel and the inlet pressure; means for subjecting the fuelflow control means to fluid pressure posterior to the metering means,and to the intermediate pressure acting in opposition to said fluidpressure; and means for varying the intermediate pressure.

6. The invention defined by claim 5 wherein the last mentioned means isresponsive to an engine variable.

7. The invention defined by claim 5 wherein the last mentioned means isIresponsive to engine charging pressure.

8. The invention defined by claim 5 wherein the engine has an intakemanifold and the last mentioned means is responsive to the manifoldpressure.

9. A fuel system for an internal combustion engine comprising aconduitfor supplying fuel to the engine; fuel metering means in said conduit;fuel control valve means for said conduit posterior to the meteringmeans; a pump adapted to be driven by the engine and having an inlet andoutlet, for supplying unmetered fuel to said metering means at avariable pressure; means for creating a fuel pressure intermediate thepressure of said unmetered fuel andthe inlet pressure; means forsubjecting the valve means to fluid pressure posterior to the meteringmeans,

audace and to the in termediate pressure acting in opposition to saidiiuid pressure; and means for vary,

ing'the intermediate pressured 10. The invention defined by claim 9wherein the last mentioned means is adapted to temporarily vary theintermediate pressure.

11. In a fuel supply system for an internal combustion engine: a conduitfor supplying fuel to the engine; fuel metering means in said conduit;fuel flow control means posterior to the metering means; 'an enginedriven pump for supplying fuel to the metering means at a pressurevarying in response to variations in engine speed; means fortransmitting a variable control pressure created by said pump tosaidfuel flow control means; means for controlling the fuel flow controlmeans by the differential of the pressure posterior to the meteringmeans and said control pressure; and means for varying one of thepressures actingon said fuel ow control means.

12. The invention defined by claim 11 wherein the last mentioned meanstemporarily causes a l diierential in said pressures.

13. A fuel supply system for an .internal combustion engine comprising aconduit for supplylng fuel to the engine; a metering jet'in saidconduit; a valve posterior to the jet; for controlling the flow ofmetered fuel; pump means for supplying fuel to the metering jet at apressure varying in accordance with engine speed; means for creating acontrol pressure; means for subjecting the valve to metered fuelpressure for urging said valve in one direction, and to said controlpressure for urging the'valve in the opposite direction; and means forvarying one of the effective pressures controlling said valve.

14. In a fuel system for an internal combustion engine: ,a conduit forsupplying fuel to the engine; a metering jet in said conduit; aregulating valve posterior to the metering `jet for controlling the flowof metered fuel; means for supplying fuel to the metering jet at apressure varying in accordance with engine speed; means for creating acontrol pressure which is normally equal to the metered fuel pressure;means for subjecting the valve to metered fuel pressure for urging saidvalve in the opening direction and to said control pressure for urgingsaid valve in the closing direction; and means for at least temporarilyunbalancing the pressures controlling said valve. l

15. In a fuel system for an internal combustion engine: a conduit forsupplying fuel to the engine; a metering restriction in said conduit; avalve in said conduit posterior to said restriction; a diaphragmconnected with said valve; pressure creating means having an inlet, andan outlet supplying fuel to said conduit anterior to the meteringrestriction at a pressure varying in accordance with engine speed; asource of fuel connected with said inlet; means for creating a uidpressure intermediate the inlet and outlet pressures of the pressurecreating means; means for subjecting the diaphragm to uid pressureposterior to the restriction and said intermediate pressure for urgingthe diaphragm in the valve opening and closing directions respectively;and means for varying said intermediate pressure.

16. In a fuel supply system for an'internal combustion engine having anintake manifold controlled by a throttle: a conduit for supplying fuelto the manifold; a metering jet in said conduit; a valve in the conduitposterior to the jet; a uuid pump having an inlet, and an outletsupplying fuel to the conduity anterior to the Jet at a pressure varyingin accordance with engine speed; a source of fuel connected to theinlet; means for creating a fluid pressure normally balancing themetered fuel pressure; means for subjecting the valve to the meteredfuelI pressure and the balancing pressure for urging the valve in theopening and closing directions respectively; and means responsive tomanifold pressure posterior to the throttle for varying one of saidpreslll'; sures.

l. 17. 'Ijhe invention defined by claim 16 wherein the lastqnentionedmeans temporarily varies the balancingipressure.

18 A fuel supply system for an internal cornbustion engine having anintake passage with a fuel discharge nozzle therein comprising a conduitfor supplying fuel to the nozzle; a metering jet in said conduit; avalve posterior to the jet for controlling the flow of metered fuel;pressure creating means having an inlet and an outlet supplyingunmetered fuel to the conduit anterior to the jet at a pressure varyingin accordance with engine speed; means for urging the valve in theopening direction in accordance with lmetered fuel pressure; means forurging the valve in the closing directionl in accordance with fluidpressure intermediate the pressure of unmetered fuel and inlet pressure;and means for varying the pressure urging the valve in the closingdirection.

19. In a fuel supply syst-em for an internal combustion engine: aconduit for supplying fuel to the engine; metering -means in saidconduit; a`

valve posterior to said means for controlling the flow of metered fuel;a movable wall connected to said valve and subjected to metered fuelpressure for urging the valve in the opening direction; a pump in saidconduit having an inlet and an outlet, and so constructed and arrangedas to create a head across said metering means pro- 40 portional to thesquare of engine speed; a source of fuel connected with said inlet; apassage connecting the outlet of said pump anterior tothe metering meanswith said inlet; a restriction inv said passage; valve means for varyingthe'eifec- '4" tive area of said restriction; means responsive to thedensity of the charge entering the engine to control said valve means;a, second restriction in said passage on the inlet side .of the iirst Hmentioned restriction; and means for subjecting the movable wall to thepressure of fluid between said restriction/sffwlereby said wall isurged' inl the valve closing direction.

20. In a fuel system for an internal combustion r engine: a conduit forsupplying fuel to the engine; ametering jet in said conduit; a valveposterior to the jet for controlling the flow of metered fuel; meanshaving an inlet supplied with fuel and an outlet for supplying unmeteredfuel to the jet, said means being adapted to create unmetered fuelpressure greater than the inlet pressure by an amount substantiallyproportional to the square of engine speed; a diaphragm connected withsaid valve, said diaphragm being subjected 6,. to metered fuel pressurefor urging the valve in the opening direction; a passage connecting saidinlet and outlet; a pair of spaced restrictions in said passage, thepressure intermediate said restrictions being a control pressure of avalue intermediate the outlet pressure and the inlet pressure andgreater than the inlet pressure by an amount equal to a constantpercentage of the difference between said outlet pressure and the inletpressure; means for subjecting the diaphragm to' the control pressurefor urging the valve in 9 the closing direction and means for varyingthe effective area of one of Suid restrictions.

21. In a fuel supply system for an internal combustion engine: a conduitfor supplying fuel to the engine; a metering jet in the conduit; a valveposterior to the jet for controlling the flow of metered fuel; an enginedriven pump having an inlet supplied with fuel, andan outlet forsupplying fuel to the metering jet at a pressure varying as a function of engine speed; a diaphragm connected to said valve and subjected tometered fuel pressure for urging the valve in the opening direction;means for creating a control pressure substantially equal to the meteredfuel pressure; means for subjecting the opposite side of the diaphragmto the control pressure; and means for at least temporarily varying thecontrol pressure. Y

22. The invention deflned by claim 21 wherein the last mentioned meansis responsive to changes in the density of the charge entering theengine.

23. The invention defined by claim 21 wherein a rise in the chargedensity entering the engine will effect a drop in the control pressure.

24. The invention defined by claim 21 wherein the last mentioned meansis controlled by the density of the charge entering the engine and isadapted to effect an increase in the flow capacity upon an increase inthe pressure of said charge.

25. The invention defined by. claimv 21 wherein there is a. pair ofsprings on opposite sides ofthe diaphragm acting in opposition. to eachother.

26. The invention defined by claim 21 wherein there is a yielding meanson each side of the diaphragm acting in opposition to each other on saiddiaphragm, the respective yielding means normally balancing each other.I,

27. 'I'he invention' defined by claim 21 wherein there is a spring oneach side of the diaphragm acting in opposition to each other on saiddiaphragm, said springs normally balancing each other; and adjustingmeans adapted to establish the normal position of the valve.

28. The invention defined by claim 21 wherein there is spring means oneach side of the diaphragm acting in opposite directions on saiddiaphragm, said springs normally balancing each other and normallymaintaining the valve in a opened position.

29. In a fuel system for an internal'combustion engine: a fuel supplypump; a connection for conducting fuel from the pump to the engine;means including a pumping member driven by the engine for deliveringfuel to the engine in accordance with variations in engine speed;

' means for varying the fuel flow to the engine as provided by the firstmentioned means; a passageway for transmitting a variable fuel controlpressure created by the first mentioned means to the varying means; andmeans for varying the control pressure as a function of' an enginevariable.

30. A pressure carburetor for an internal combustion engine, saidcarburetor having an induction passage anda source of fuel underpressure:

an engine driven pump which receives fuel from said source and generatespressure in proportion to the square of revolutions per minute of theengine; a conduit from the pump to the induction passage; a meteringorifice in said conduit; a movable wall; means for admitting fuel to oneside of the wall; a restriction in said means; a fuel chamber associatedwith the movable wall on the opposite side thereof in which metered fuelpressure is maintained; a valve controlling the outlet from the chamber;and means responsive to the charging pressure of the engine foreffecting control of the position of said valve.

31. In a fuel supply system for an internal combustion engine having anintake manifold controlled by a throttle: a fuel pump adapted to deliverfuel at a substantially constant pressure; a conduit connecting saidfuel pump with the induction passage posterior to the throttle: ametering jet in said conduit; a valve posterior to the metering jetforcontrolling the flow of fuel; a diaphragm connected to the valve; ametered fuel chamber on the valve side of the diaphragm; a second'fuelchamber, on the opposite side of said diaphragm: opposed balancedsprings in said chambers urging the diaphragm in oppositey directions;an engine driven pump. including a rotor, adapted to produce an increasein pressure of unmetered fuel proportional to the square of enginespeed; a fuel passage connecting the outlet and inlet sides of' thepump; a pair of restrictions in the fuel passage arranged in series;means connecting the second chamber with said fuel passage intermediatesaid restrictions; a valve controlling the effective area of therestriction directly subjected to unmetered fuel pressure; and a bellowscontrolling said `valve in accordance ,with the pressure in the intakemanifold posterior to the throttle.

32. The invention defined by claim 31 and including a fuel nozzle in theinduction passage; and means for bleeding air to said nozzle,

33. A fuel feeding device'for an engine, comprising a. fuel conduithaving a fuel metering orifice therein, a centrifugalpump in the conduitadapted to be rotatably driven by the engine for increasing the pressureof the unmetered fuel `supplied to the orifice with increase in enginemeans for increasing the metering differentialy pressur'e across saidorifice with increase in engine load, said last named means comprising avalve in the conduit posterior to the orifice for varying the meteredfuel pressure in accordance with `a variable representative ofvariations in engine load at a given engine speed.

35. In a fuei feeding device for an engine, a'y main fuel conduit forsupplying fuel to the y engine, a fuel metering orifice therein, a fuelpump having a fuel inlet for receiving fuel from a source and an outletfor supplying fuel to the orifice under a pressure greater than thepressure in the inlet by an amount varying substantially as the squareofthe pump speed, a by-pass from the pump outlet to the pump inlethaving two restrictions in series therein, a fuel control valve in theconduit posterior to the metering orifice,

a movable pressure responsive wall connected to said valve and arrangedto be subjected `to the pressure in the by-pass between thevrestrictions for urging the valve toward closed position and tothe'pressure of the metered fuel for urging the valve toward openposition, and valve means for varying the effective varea of one of saidrestrlctions. 1

36. In a fuel metering device for an engine: a main fuel supply passagehaving in series therein a centrifugal impeller adapted to be driven bythe engine, a metering orice, and a flow control valve, said impellervarying the pressure on the upstream side of the metering orifice withvariations in speed of the impeller; a by-pass passageway leading fromthe fuel supply. passage between the impeller and orice to the fuelsupply passage anterior to the impeller, said passageway having tworestrictions in series therein; and a member responsive to the pressurein the passageway between the restrictions for controlling said nowcontrol valve.

37. The fuel metering device dened in claim 36 comprising in addition avalve means for varying'` the relative effective areas of the tworestrictions, and a device responsive to variations in the pressure ofthe air supplied the engine for controlling said valve means.

38. A fuel metering device for an engine comprising a centrifugalimpeiler adapted to be driven by the engine, a fuel inlet passage forsupplying fuel to the impeller, an outlet passage into which theimpeller discharges fuel under a pressure varying with variations inimpeller speed, a metering crice in thenoutlet passage, a conduitconnecting the outlet passage anterior to the metering orifice to theinlet passage, two

restrictions in series in said conduit, and a valve l30 2,374,844

in the outlet passage posterior to the metering orifice responsive tothe pressure in the conduit between said restrictions.'

39. The invention ldefined in claim 38 comprising in addition a memberfor varying the eiec- 35 tive area of one of said restrictions.

40. In a fuel feeding device for an engine or the like: a centrifugalpump adapted to receive fuel through an inlet from a source and todischarge said fuel into a passage, a metering oriilce in the dischargepassage, a valve in the passage posterior to the orifice, a passagewayinterconnecting the discharge and inlet of the pump and having twocalibrated restrictions in series therein. means responsive tovariations in the pressure in said passageway between the restrictionsfor'controlling said valve, a main control element for controlling theenergy output of the engine or the like, and means operated in responseto conditions vobtained by the movement of said element for varying theeffective size of one of said restrictions.

FREDERIK BARFOD.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,189,705Chandler Feb. 6, 1940 2,290,921 Udale July 28, 1942 2,303,998 Holley,Jr. Dec. 1, 1942 2,324,599 Schorn July 20, 1943 2,372,356 Chandler-..'Mar. 27, 1945 Stokes May 1, 1945 FOREIGN PATENTS Number A y CountryDate 429,682 y Great Britain June 4, 1935 Certicate of Correction PatentNo. 2,456,603. December 14, 1948.

FREDERIK BARFOD It is hereby certified that errors appear in the printedspecication of the above numbered patent requiring correction asfollows:

Column 4, lines 13 and 53, column 5, lines 22 and 61, column 6, line 2,for valve 67 read valve 68; line 28, claim 3, after engine str ike outthe semi-colon; line 29, strike out the word means; column 12, line 7,claim 40, after discharge insert passage;

and that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent OHice.

Signed and sealed this 7th day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommsszoner of Patents.

